Bill Leonard measures the height of an Evenki teenager in one of their herding camps in Central Siberia. This information is used to further understand aspects of physical growth and the health status of the Evenki. (photo courtesy of Bill Leonard)

Following is an interview with Bill Leonard, assistant professor of anthropology.

What field of anthropology do you study?

My background is in biological anthropology. The goal is to understand the origin and the nature of human biological variability. That is, what are the reasons that we as a species today are so biologically diverse.

My research is largely field-based, working with people living in various distinct environmental and social settings. I've worked in Latin America (Peru and Ecuador) and currently in Central Siberia, Russia.

What populations are you studying in Central Siberia?

My colleagues and I are looking at a population of reindeer herders (the Evenki) because they live in a particularly harsh environment. It's a very marginal kind of environment where they're being exposed to extremes in temperature and day length. The climate limits any agricultural base so the diversity of foods available to them is relatively limited. They must also live with drastic seasonal changes - daylight ranges from 24 hours a day to virtually none in the winter.

How do you conduct your research?

We visit these remote locations and ask people about various aspects about their lifestyle. We also measure certain important biological traits including growth and development, energy intake and energy expenditure.

Our research shows that they eat 2 1/2 to 3 times more meat and animal material than we do. They also consume about 2,500-3,000 calories a day, which is quite a lot for people who are only 4'10" - 5'2" tall and 110-120 pounds. Despite this unorthodox diet, however, we've found that they have unusually low cholesterol levels and low body fat content.

So although the Evenki are living in extreme conditions and eat what we would consider an unhealthy diet, they're still relatively healthy. What's your explanation for this?

Our data indicate that their metabolic rates at rest are higher than what we would have predicted. Why? We think it's because of the cold environment. They're using more calories at rest to maintain body temperature. Also, because they are highly active, their total daily calorie requirements are high. Consequently, the balance between calorie input and calorie output is about equal which explains why they're not gaining weight. The other thing that factors into this is unlike the meat that we eat in this country, their meat is very lean and low in saturated fats.

What does this mean to your research?

We're trying to understand whether or not these distinct aspects of physiology - increased energy requirements - are a short-term response or if there's something unique genetically about these people that allows them to respond the way that they do. In other words, do they have a distinct biological adaptation by virtue of the fact that for generations they've been exposed to this climate?

How will you begin to answer that question?

The way we're addressing that issue is by comparing the Evenki who have lived in Siberia for many generations to a group of relatively recent Evenki who migrated from Moscow or other parts of the former Soviet Union.

Are they similar or are they different? If it's genetically based, then we expect that the Evenki should show very different responses to these environmental stresses than the recent migrants. If it's a short-term kind of response to the environment, then the Evenki and Russian migrants should be similar. We're just now beginning to look at some of that data and our preliminary results do suggest that there is some degree of genetic differentiation.